Bicycle frame



FIG. 1 is a right side elevation of a bicycle frame of our new design having a flat side, shown as might optionally be used with surrounding structure, which is shown in broken lines for illustrative purposes only and forms no part of the claimed design;

FIG. 2 is a top elevation of a bicycle frame according to of our new design;

FIG. 3 is a bottom elevation thereof;

FIG. 4 is a front elevation thereof; and,

FIG. 5 is a back elevation thereof.

The left side elevation of a bicycle frame according to our new design is a mirror of the bicycle frame illustrated in FIG. 1. 

The ornamental design for a bicycle frame, as shown and described. 